In these lean times, fiction is putting on weight. Take three of the major novels out in the next few weeks. Never mind the quality, which is variable, feel the width. Angelmaker (Heinemann), Nick Harkaway's second novel, weighs in at 576 pages. My copy of Capital (Faber) by John Lanchester tips the scales at 577pp. The Bellwether Revivals by Benjamin Wood (S&S) is a 420-page debut. Even the Costa winner, Andrew Miller's Pure (Sceptre), runs to a chunky 352 pages. When last year's Booker winner, The Sense of an Ending, was first shortlisted, there were some who said that, at 150 pages, it wasn't really a novel. Whatever happened to the slim volume?

You can blame the computer for the contemporary writer's reluctance to cut. Again, you can blame the decline of editing at the big imprints, which is actually more apparent than real. Or you can point the finger at the pressures of the marketplace, especially in America.

The jury is out on all these charges. Fatter novels are the outcome of these and many other factors. What's hardly in doubt is that where novelists used ascetically to follow a regime of "less is more", now they're piling on the carbs.

This trend towards fiction of between 350 and 500-plus pages is new. Graham Greene, whose prose was always pared to the bone, wrote of learning his craft as a subeditor on the Times: "A sprawling style is unlikely to emerge from such an apprenticeship." For much of the 20th century, novels averaged 75,000 to 80,000 words, making a book of fewer than 250 pages and sometimes barely 200. Further back, the picture becomes more complex.

While we can doff our caps to Thackeray, Trollope and the triple-decker Victorians, we should recognise that some of English literature's best-loved classics are exceedingly short. The recent celebration of Dickens's 200th birthday has given a new lease of life to Nicholas Nickleby and Bleak House, which are 800pp and more than 1,000pp, respectively. But the Dickens story everyone loves is A Christmas Carol, which is 160 pages, even with illustrations.

In the minds of many readers, Henry James is associated with orotund monsters such as The Wings of the Dove and The Golden Bowl. Actually, the master's masterpiece, to which generations of readers are drawn like iron filings, is The Turn of the Screw, which is just 128 pages short.

James's brilliant near-contemporary, Robert Louis Stevenson, defied the gravity of the age with a sequence of short classics, notably Dr Jekyll and Mr Hyde and Treasure Island. Stevenson used to say that "the only art is to omit". Tell that to Messrs Harkaway, Miller and Wood.

The more you look for brevity, the more you find it flourishing in the shadow of fiction's spreading oaks. Herman Melville is now celebrated for that archetypal long novel, the baggy Moby-Dick, his American masterpiece. But Melville is also the author of Bartleby the Scrivener, well under 100 pages, an existential thriller.

Possibly the greatest short novel ever written, the haunting, hypnotic pages of Conrad's Heart of Darkness are as rich, strange and savage as anything since. Conrad wrote it in a just over a month in December/January 1898-9. It's about 38,000 words. EM Forster, another Edwardian, nailed the vanity of discursive novels with this note in his Commonplace Book. "Long books," he wrote, "are usually overpraised, because the reader wishes to convince others and himself that he has not wasted his time."

Short books, in brief, form a vigorous alternative tradition. This is a line of fiction that runs deep into the last century and illuminates the reputations of many great writers. Animal Farm is short, and so is Beckett's incomparable Ill Seen Ill Said and Muriel Spark's The Prime of Miss Jean Brodie.

Across the Atlantic, the source today of so many long novels, Truman Capote (Breakfast at Tiffany's) and Philip Roth (Goodbye, Columbus) never wrote better than when they wrote short. The greatest American fiction of the 20th century, The Great Gatsby, is about 58,000 words, or 192 pages in my Penguin classics edition.

So, when book clubs in the depth of winter complain, after the humorist Ambrose Bierce, that "the covers of this book are too far apart" they should look out for something short. It's not fashionable, but it might educate and entertain.

Buster's sporting life is music to anybody's ears

I was pleased to see that The Artist won a Bafta for best original screenplay. Cinema this good does not grow on trees. And now the influence of the film is spreading. I hear that the Bath literary festival has "gone totally mad" in the words of its director, novelist James Runcie. He plans a screening of Buster Keaton's College, in which a bookish young man throws off his love of literature and attempts to win the girl he loves by entering a series of sporting events for which he is hopelessly unqualified. The film will be accompanied by music from a group of talented players who have never seen it before. Runcie, never lost for words, declares this screening will be a "unique, spontaneous, terrifying and hilarious one-off event".

Silence is golden.

All aboard the Charles Dickens gravy train

One of the strangest titles to have been inspired by the Dickens bicentenary, for trainspotters everywhere, must be Charles Dickens's Networks: Public Transport and the Novel by Jonathan Grossman (OUP). Taking Pickwick as his starting point, Grossman explores the decline of the stagecoach in Dickens's novels, culminating in Little Nell's "fatal intercity trip" in The Old Curiosity Shop and the transcontinental movements of "fellow travellers" in Little Dorrit. This must be the first occasion in which railway timetables have contributed to the evolution of the novel. Sadly, for the full deployment of his argument, Grossman fails to explore the moment in 1865 when The Inimitable was nearly killed in a serious railway accident at Staplehurst. That's the kind of impact that might have really changed the novel.